roachtest/cdc: remove dead cluster settings from roachtest/cdc

Previously, we removed relevant cluster settings to
`jobs.registry.retry.initial_delay` and `jobs.registry.retry.max_delay`
in #135825 but didn't remove its usage from
`cdc/initial-scan-rolling-restart`. This patch removes its
usage from roachtest/cdc.

Fixes: #135973
Fixes: #135974
Release note: none

pkg/cmd/roachtest/tests/cdc.go

@@ -1043,8 +1043,6 @@ func runCDCInitialScanRollingRestart(
 		`ALTER TABLE large SCATTER`,
 		fmt.Sprintf(`CREATE TABLE small (id PRIMARY KEY) AS SELECT generate_series(%d, %d)`, largeRowCount+1, largeRowCount+smallRowCount),
 		`ALTER TABLE small SCATTER`,
-		`SET CLUSTER SETTING jobs.registry.retry.initial_delay = '.1s'`,
-		`SET CLUSTER SETTING jobs.registry.retry.max_delay = '.4s'`,
 	}
 	switch checkpointType {
 	case cdcNormalCheckpoint: